Abstract - Although continents were coalesced into the single landmass Pangea, Late Triassic terrestrial tetrapod assemblages are surprisingly provincial. In eastern North America, we show that assemblages dominated by traversodont cynodonts are restricted to a humid 6° equatorial swath that persisted for over 20 million years characterized by “semiprecessional” (approximately 10,000-y) climatic fluctuations reflected in stable carbon isotopes and sedimentary facies in lacustrine strata. More arid regions from 5–20°N preserve procolophonid-dominated faunal assemblages associated with a much stronger expression of approximately 20,000-y climatic cycles. In the absence of geographic barriers, we hypothesize that these variations in the climatic expression of astronomical forcing produced latitudinal climatic zones that sorted terrestrial vertebrate taxa, perhaps by excretory physiology, into distinct biogeographic provinces tracking latitude, not geographic position, as the proto-North American plate translated northward. Although the early Mesozoic is usually assumed to be characterized by globally distributed land animal communities due to of a lack of geographic barriers, strong provinciality was actually the norm, and nearly global communities were present only after times of massive ecological disruptions.

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About Me

My name is Bill Parker and I am a paleontologist in northeastern Arizona. While my day job mainly involves roaming the badlands of Petrified Forest National Park picking up bit after bit of phytosaur scrap (and finding some good stuff in-between), thus my main focus is the paleontology of the Triassic Period. However, I also have a very strong interest in Civil War history, and am a direct descendent of veterans who fought on both sides. Note: This is a personal site and all posts are my own opinions and do not represent the opinions of the National Park Service.